Cervical length

Last revised by Dr Mostafa El-Feky on 15 Apr 2020

In obstetric and gynecological imaging, the cervical length is defined as the distance between the internal cervical os and the external cervical os.

Radiographic assessment

  • the cervical length is most accurately assessed on a transvaginal scan with an empty bladder
  • in a normal gravid situation, the cervical length is considered to be at least 30 mm (3 cm)
  • the presence of a full bladder can increase the cervical length particularly on a trans-abdominal scan

See also

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Cases and figures

  • Case 1: normal second trimester scan
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